Kindara is my favorite app for fertility awareness. It doesn't try to "predict" your fertile days; it helps you understand how to interpret your fertility for yourself. (For example, you'll have to draw your own coverline and enter your own Peak Day, but it will count the days of your luteal phase for you). It's clean, simple, and powerful. And with Wink, their silent and wireless BBT thermometer, they couldn't make it any easier to seamlessly track and interpret your fertility signs.

FertilityFriend is an extremely powerful app, designed for the serious charter. Although the app design itself leaves much to be desired, it packs a punch under the hood. However, it can be too much too soon for some starting charters. FertilityFriend offers free and premium options for charting. Most women are fine with free, but premium offers some major perks to anyone serious about fertility awareness.

Tracks BBT, cervical fluid, and cervical position

Estimates ovulation for you with "crosshairs" (which you can change if the date is wrong)

Lets you search for and view other users' charts by topic, category, or type